Why does email bounce?
Hi everyone, Leo Notenboom here
for Askleo.com. Here's a question I got and it's a common one.
"Sometimes my email bounces.
Every so often I'll send a message
and a short time later I'll receive
a reply saying that the email failed to go through.
Why does this happen and how do I fix it?"
There are so many reasons email can bounce.
I can't give you an answer, but
we can certainly go over most of the more common reasons that you might
get a bounce message back.
So first of all, what is an email bounce?
Now, an email bounce is exactly as described in the question.
You send a message to someone and instead of getting a reply from them
or not hearing anything because they received it, you get a message back
from an email server that says your message didn't make it through.
Now, most of those messages actually
include information about why. It's not standard the words they use.
It's also not very friendly.
It's often very difficult to understand exactly
what the message is trying to tell
you other than it didn't work.
Usually there's good information in the headers or in the response, and I would
strongly suggest that you just take a
few minutes, take a second and browse
through exactly what those messages are trying
to tell you, because more often than
not, they're trying to tell you what went wrong.
Here's one example.
So this is an example obviously I've
constructed, but the bottom line is that it says a couple of different things.
Relaying denied from your location. Somewhere@example.com.
User unknown.
Well, the user is unknown.
That email address, whatever it might be,
in this case somewhere@example.com, it doesn't exist.
It's wrong.
Here's another example that tries to be
a little bit more friendly.
Does not like recipient mailbox not found.
Mailbox not found once again means
that there's something wrong about that email address.
That email address does not have a place for email to go.
It doesn't exist.
Those are probably the most common messages
or class of messages that you're likely to get.
The very first thing absolutely.
The number one thing you need to
check whenever you get an email bounce is the email address
correct? The email address in that error message, because if you sent to multiple
people at once, it may go through to some of them.
But if even just one of them
fails, you'll get a bounce back.
You'll need to look at that error
message, that bounce, to see which email
address this applies to.
Make sure that email address is correct, make sure you didn't typo it.
Make sure that there wasn't a typo
automatically filled for you.
Which happens a lot
as it turns out. If you happen to typo
once, then your browser or your web program or your email
program may try to help you by remembering for you and trying to fill
it in for you. Even though it was a mistake.
I've got articles on how to remove
that from the remembered list of things that it tries to help you with.
But the very first thing, the number one most common reason for an email
bounce is an email address that is simply incorrect.
So let's take a look at some
of the other error messages
Besides Mailbox Not Found or User Unknown that might be part of a bounce message.
Mailbox Unavailable. To be honest, nine times out of ten, this is exactly the
same as Mailbox Not Found.
It means the email address doesn't exist.
There are scenarios where it can mean something else.
It can mean that the email service is having a problem.
It literally can't get to the email address that it knows exists.
It may be any of a number of different things.
This is one where if you get a bounce you want to wait a little while.
I would wait, I don't know, an hour or two or a day and then send it again.
If you get the same message again,
then something's probably permanently broken and you
want to try and contact your recipient some other way.
Mailbox Full or Quota Exceeded.
This means that the email address is probably right, but the recipient has
received so much email that they've exceeded the amount their
email service allows them to hold.
They need to begin deleting or arranging
or moving email to make room for more messages to be able to arrive.
Until they do so, you and everybody
else trying to send an email will
get this bounce message that says. No.
They don't have enough room for email.
You need to contact them some other way.
Host Unknown Domain Lookup Failed. In the example that I used above
somewhere@example.com, this is telling you that specifically
the example.com part of it, the part after the @
sign has a problem. It's got a typo.
It's a domain that doesn't exist.
Obviously example.com exists.
But if you typode it, or
if it's an old email address for
a domain that's no longer in use, or any number of other things,
it's telling you that the domain part is wrong.
It can't even check the email part.
The part before the at sign, the part after the at sign.
We don't even know how to reach their service.
Unable to Relay. This is a very obscure message.
That usually means there's a configuration error in the email server or an email
server along the path from your email to that of your recipients.
Relaying is simply the act of a
mail server receiving email and then
passing it on to the next email server in the chain.
Unfortunately, because that was so heavily abused
by spammers, it's typically not allowed.
It's typically denied.
And that's why I say unable to
relay or Permission Denied or any number
of related messages to relaying typically means
that there's something wrong about
the configuration of the email servers itself. Because they
shouldn't necessarily be relaying
in cases where they aren't allowed to relay. There are ways to make it
permissible, but for some reason, something isn't working.
Go back to what you do have control over,
and that is making sure that you are sending to the right email address,
that you are properly Authenticating with your own email service provider.
But otherwise, again, another case of you may need to try
and find out if you got the correct email address or if that person is having
problem with their email. Contact them some other way.
Now, there are typically a number of
so called temporary errors.
I've written in other articles that email
was actually never intended to be instant.
It was never intended to even necessarily be quick.
The protocol actually handles delays
of multiple days, which is kind of interesting in.
Today's fast paced society.
You may find errors like no adequate servers or connection timed out,
or resources temporarily unavailable and out of memory.
All those kinds of things, those are all temporary.
If you look at the error message closely,
you will find out that it's probably going to tell you that it's
going to continue to try.
In other words, the message that you're
getting, the bounce that you're getting doesn't
necessarily tell you that something has failed.
It just tells you that it hasn't worked yet.
It's a warning. It's telling you that your email is not
going to get there quite as quickly as you might have expected.
Generally, if it is a hard error, if it's a real problem that is permanent.
Three, four, five days later, you'll get
a bounce that says, you know what? I gave up.
I can't do it.
Something isn't working.
We're just unable to get this message through.
That's the hard bounce that tells you your message failed.
Blacklists are another one.
Again, to go back to spam for a minute.
Antispam measures are incredibly complex.
There are many, many things that factor
into exactly what email services use
to determine whether or not something is spam.
Sometimes, though not always, if you send
something that they determined to be spam, you may get a bounce.
You may not.
It may be silently discarded, or it may go into the user's spam folder.
But if you get a bounce that includes things like blocked or listed in or
blacklist or deny lists, and you have seen names like Spam, Cop, Dynablock.
Black Hole, Spam House, and similar, then
there's a very good chance that for one reason or another, your email has.
Been flagged as spam, it may not be your fault.
Obviously, make sure the message you're
sending isn't spam and doesn't look spammy.
But spam also looks at things like the reputation of the email service you're
using, the reputation of the specific email.
Server used by the service that you're
using, the email reputation of your domain.
And potentially even your email address itself.
So these are all things that can
factor in. But if you get a message that includes terms like that, then.
You know your message has probably been bounced back to you because
for reasons legit or not, your message has been flagged as spam.
The same thing is very true for content filters.
In other words, if you're using words
that for whatever reason, the receiving side
doesn't think is appropriate or they want to prevent from getting sent through, and
this is usually words that you find
very commonly in spam, then you may run into that same problem as well.
One of the common pieces of advice
of course, is to try again in a while.
Well, how long is a while? Especially
for some of these transient errors, it.
Can be really hard to know.
There is no specific answer to this.
My rule of thumb is to try again in a few
minutes, try again in a few hours, try again in a few days.
If it still doesn't work and you
can wait that long, then you've got a hard problem.
If you can't wait that long, then you've got a hard problem.
And in both of those cases, the only thing you can really do is to
reach out to your recipient some other way.
Now there is one thing I definitely.
Need to talk about, and that is
sometimes you'll get bounces to messages you did not send.
Don't act on those.
You can look at them if you like.
You can see if there's anything
interesting in them to make sure that it is something that you didn't send.
But it's really common and all that is is spam.
There are two scenarios where that will happen.
One is it's legitimate spam if there is
such a thing that was sent from your email address.
In other words, this email was crafted to be forged to look like it came from you
so that when a bounce eventually happened, it comes back to you.
If you didn't send it, don't act.
On it, just delete it and get
on with your life.
The other scenario, of course, is that
spammers will sometimes make their
original message look like a bounce message and encourage
you to act on it,
to click the links on it, to take action based on what they've sent
you. Don't. If it's a bounce, you
don't expect if it's a bounce to
a message you did not send, don't act on the bounce.
Finally, if everything is bouncing,
absolutely every email you send is bouncing.
That's usually a sign that your email
client or your email program is somehow misconfigured.
Make sure you're connected up to your email service provider properly,
because if everything is bouncing, that's a problem right there at that first line.
I hope that helps explain a little
bit of why email might bounce.
What some of the messages are,
what some of the actions you may or may not want to take are as
a result. For updates, for comments,
for related links and more visit askleo.com/11192.
I'm Leo Notenboom and this askleo.com. Thanks for watching.